Corner construction for folding boxes



y 28, 1953 R. B. MELLER 2,646,916

. CORNER CONSTRUCTIONFOR FOLDING BOXES I Filed Nov. 30, 1949 v 4 Sheets-Sheet l INVENTOR. REGINALD a. MELLER BY AUSTIN, W/LHELMQ- CARZSON #W' 6- W ATTORNEYS July 28, 1953 R. B. MELLER ,9

I CORNER CONSTRUCTION FOR FOLDING BOXES Filed'Nov. so, 1949 4 Sheets-Sheet 2 INVENTOR. REGINALD B. MELLER AUSTIN, W/LHELM 8'. CARLSON W 5- W2.

July 28, 1953 R R. B. MELLER 2,646,916 r CORNER CONSTRUCTION FOR FOLDING BOXES Filed Nov. 30, 1949 4 Sheets-Sheet s Fig. 6

- QNVENTOR.

" REG/NALD B. MEL/.51? BY Ausrm; W/LHELM a c nzsozv u y 8, 1953 R. B. MELLER r 2,646,916

CORNER CONSTRUCTION FOR FOLDING BOXES Filed Nov. 30,.1949 4 Sheets-Sheet 4 INVENTOR. REGINALD a. MELLER Fig. 12 BY i v AUSTIN, W/LHELM & CARLSON A TTORNE Y3 boiihtered when it is Patented July 28, 1953 UNI TE -D STATES PAT EN T ()F F ICE 2,646,916 I 001mm CONSTRUCTION FOR FOLDING BOXES Reginald B. Meller, Oakland, Calif assignor to Bemiss-Ja'son Gognpany, San Francisco, Calif.,

a corporation of California Application November 30, 1919, Serial No. 130,229

9 Claims.- (01. 229-45) This invention relates to improvements in eart'ons, boxes, trays, and other structures, hereinafter collectively referred to as boxes or folding boxes, made, by folding-10m blanks of cardboard, pa erboard, er other suitable 'ioldi'ng sheet material.

The invention has particular application to the type of foldingb'oxes which are maintained in assembled cohdi by 'gliieles's-i hterengag'emen'toi certain port nscf the box blank.

The art of assembling ioldi'ng boxe'sbyji nterengagement of portions of the box blank without the iise of adhes' is many decades old, and many "different terms oi locks have been proposes for forming box terriers. The majority of the locks heretofore proposed are designed for hand assembly.

"'erabie difiiculties are enattem ted to set up and engage co ventional looks by mechanical equi ihent. Other known forms of locks suited for assembl by machines "gene-min require equi me'nt which is complex or slow.

The present invention is concerned with certain improvements in the "corner construction of folding boxes which result in a more secure lock than has heretofore been available, and a lock which can be "formed on automatic high speed 'roaehinery or compact design and relatively simlpl'e (:CifiStlilfitlOll. The invention hl'bl'e particularly provides an intefloek, or box corner con- "s'tr'oction, which is far more attac'tive in appearanee "than corner constructions of previous- 1y known design, in that flaps or tabs by which the interlocking is accomplished, and which is known forms or looks are quite 'conspi'c'ious, are arranged in such a way as to be pi'aeti'cally eonhealed. This improvement opens to boxes of the l'glueles's type a rareer field of application which heretofore was Closed, either because of consumers? resistance to onspieioiis lock naps i tabs, or because of technical di'fieul'tie's encountered with exposed filDS 9316. 't'abs which interfere, at least in some measure, with the use of telescopin; covers, the use of overwra'ps, the use of hinged covers, and the p'aoka'g'ih'g' of seen boxes in larger receptacles because oi the nan-get of flaps or tabs of one box becoming entangled with those of another. v

The invention further provides an improved form of oorhe'r eonstruction 'whioh is particularly rigid and resistant to pressure by the contents of the box against the inside of the box "Corner. This is accomplished by a construction in which two plies of stock are pro -idea an arrangement that pres o-re of the box Gdiitil'ts flees 2 not tend to disengage the interengaging portions of the lock itself.

Glu'eless interlocks incorporating the present invention 'can be formed on automatic machinery at extremely rapid rates' oi the order of to over 200 boxes a minute, depending on box size.

Boxes equipped with the improved corner lock incorporating this invention may be set up, and the box walls locked simultaneously at all four corners by a plunger and die arrangement of relatively simple and dependable construction con taining very few parts which are so arranged that it is practically impossible for them to get out of adjustment. This is a fea'ture of considerableimportance for machines installed in a customers plant Where the production of the box forming machine is used immediately for the packaging of goods produeed in a continuous process. It is evident that in such plants the dependability of the box machine is a factor of even greater importance than the dependability of a box machine operating in a box makers plant, since the production of the box machine is not "stocked. but used immediately.

The corner construction provided by this invention is particularly suited for lme'd boxes, the construction of the various elements "of the box corner being such that the liner is automatically guided into formation of a neat bellows or gusset while the box is being set up. -A particular feature of the invention resides the fat-it that lined boxes can beset up by the same mechanical equipment which "is used for setting up boxes without a liner These and other objects, features and advantagesof the invention will appear more fully from aeonsizieia'tion of the 'c letaileol description when follows accompanied by drawings showing, for the urpose of illustration, preferred einbodiments and applications of this invention.

The invention also consists in bert-ain new and improved details of construction as hereinafter set forth and claimed. 1

Although the har'acteristio features of the invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention, its objects and advantages, and the manner in it may be -'ca'rried out, may be better understood by referring to the following oeseription taken in connection with the accompanying drawings forming a part of in which:

Figure 1 is a plan view of a hat box blank ethbodying the invention, the inside surface of the blank facing the observer,-

Figure 2 is a perspective view of the box set up from a blank shown in Figure l, the box being shown in the position in which it leaves the automatic box forming and corner locking machine;

Figure 3 is a perspective View illustrating the formation and locking of a box corner as the blank is being forced through a folding and looking die by a plunger;

Figure 4 is a plan View, on an enlarged scale, of the corner portion of the blank of Figure 1 with a liner;

Figure 5 is a perspective view of a box corner formed from the lined blank of Figure 4 Figure 6 is a plan view of the corner portion of a blank, the construction of the blank bein modified to provide for a bellows fold at the boX corner;

Figure 7 is a perspective view of the inside of a box corner made from the blank of Figure 6;

Figure 8 is a perspective outside view of the box corner of Figure 7;

Figure 9 is a plan view of a corner portion of a blank including a modified form of lock which is particularly inconspicuous in appearance;

Figure 10 is a perspective view of a corner set up from the blank of Figure 9;

Figure 11 is an outsidev view of a box corner made from the blank shown in Figure 9 and including a safety locking tip, the lock being shown before movement of the tip into its operative position; and

Figure 12 is a perspective inside view of the box corner of Figure 11 with a locking tip in operative position.

In the following description and in the claims various structural details will be identified by specific names for convenience. The names, however, are intended to be as generic in their application as the art will permit. Corresponding reference characters refer to corresponding parts in the several figures of the dawings.

In the drawings accompanying, and forming part of, the specification, certain specific disclosure of the invention is made for the purpose of explanation of broader aspects of the invention, but it is understood that the details may be modified in various respects without departure from the principles of the invention and that the invention may be applied to other structures than the ones shown.

The blank A shown in Figure 1 is particularly desi ned for the packaging of frozen foods. It illustrates the applicability of the invention to folding box of relatively complex construction including a box body, a hinge cover and numerous flaps on the body and on the cover. Blanks of the type represented by blank A can be set up on a fully automatic box machine at the rate of about 100 boxes per minute, assuming a blank size for a box of one pound average content. Automatic box machines for setting up the box of this size at the given rate are rather small and do not require more than approximately 3 feet by 4 feet of floor space.

High production rates are obtainable by reason of certain structural details of the corner construction of the box which permit the box to be formed into shape and the corners to be locked within a fraction of a second. The assembly operations are performed blank by blank, in the sense that the assembly operation on one blank does not begin before the assembly operations on the preceding box are completed. This procedure is in contrast with the procedure of a conventional folding and gluing machine in which ordinarily several blanks are being handled simultaneously. With this in mind the importance of structural details of the blank will be appreciated.

The blank A shown in Figure 1 may be cut, in multiple, from large sheets or rolls of paperboard, cardboard, or other suitable foldable sheet material on automatic cutting and creasing machines. The blank A is subdivided by scored fold lines into a plurality of panels, flaps, and tabs articulated to one another. A front panel il, a bottom panel i2, a back panel l3 and a cover panel [4 are hingedly interconnected along fold lines l5, l6 and H. A front fiap it is hingedly connected to the front panel H along a fold line I9 interrupted by a cut 263 for insertion of a locking tab 2i therethrough, the locking tab being hingedly connected to the cover panel i along a fold line 22. Side wall panels 23, and 2d are hingedly connected to the bottom panel i2 along fold lines 25 and 26. These side wall panels have internal cuts 2] and 28 therein for insertion of side flaps 29 and 30 hinged to the cover panel !4 along fold lines 3| and 32.

The box corner construction includes corner flaps 33, 34, 35 and 35 hinged to the wall panels H and i3 along side fold lines 3?, 38,. 3% and 2-0 respectively. These side fold lines may be slightly offset with respect to the base fold lines 25 and 26 to compensate for the thickness of the board.

The corner construction further includes lock tabs All, 62, :23 and A hingedly connected to the side wall panels 23, 24 along side fold lines 45, 56, 6i? and 48. These side fold lines may also be offset slightly with respect to the base fold lines i5 and i6 for the same reason. The lock tabs ii, 52, 33 and 4:": are insertable into internal cuts &8, 56, 55 and 52. These internal cuts are of bent outline and form internal tongues 53, 54, 55 and 5c in the wall panels ll and i3 pointing towards the box corner. The internal cuts extend substantially to the side fold lines 3?, 38, 39 and it. Preferably they xtend slightly beyond the side fold lines to provide for a self opening aperture at the side fold line, when the corner flaps 33, and 38 are folded with respect to the wall panels to which they are attached. However, it is not absolutely necessary that the internal cuts til, 50, 5! and 52 extend beyond, or even exactly to the side fold lines 37, 38, 39 and 46, it being sufficient that the cuts extend close enough to the side fold lines that an aperture is automatically formed upon folding of the corner flaps. This result is obtainable even with an internal out which does not extend entirely to the side fold line, since the inherent stiffness of the board causes the stock above and below the internal tongue defined by the cut to curve slightly at the fold line at which the corner flap is folded, whereas no curving occurs within the body of the internal tongue. The curving of the stock may be sufficient to expose an aperture at the internal cut of a width sufiicient for ready insertion of the lock tab associated with the internal cut. Nevertheless, it is generally preferred to extend the internal cut to, or slightly beyond, the side fold line about which the corner flap is folded.

The lock tabs 4!, B2, 43 and id include tip portions 51, 5B, 59 and 68 preferably arranged at the same distance from the base of the box corner proper, as the widest portion of the self opening aperture formed by the internal cuts :39, 5%, 5| and 52.

The lock tabs have locking edges 6|, 62, 53 and {54 adapted to engage the portion of the respective internal out which lies immediately adjacent the respective side fold line. Thus for example, the

formed by the internal cut 49, the corresponding edges at the other corners being lit, 61 and 68.

The corner flaps 33, 34, 35 and 36 are preferably of substantially triangular shape although other shapes are. suitable. The edges 69, it, H and 12 of the corner flaps extend substantially at an angle of 45 degrees with respect'to the side fold lines 31, 38, 39 and 40. The advantages of the triangular shape will become apparent hereinafter.

Mechanical equipment for setting up the blank of Figure 1 in a box shape may be of relatively simple construction and consists, basically, of a plunger for engaging the bottom panel is and forcing the blank through a substantially rectangular die aperture. This causes the front and back walls H and it as well as the side walls 23 and 24 to be folded into vertical position with respect to the bottom panel l2. Simultaneously the corner flaps 33, 3'6, 35 and 35- are also folded with respect to the wall panels to which they are attached. This opens apertures at the side fold lines 31, 38, 39 and 623 into which the lock tabs ll, 42, 43 and M are guided, with their tip portions 57 58, 59 and 60 leading.

A particularly simple and reliable form of folding and locking die with its associated plunger, as far as it is pertinent to the understanding of the assembly operation is shown in Figure 3.

The plunger is essentially a box-like structure preferably made of welded steel plates and comprising a base plate for engaging the bottom panel l3 and four upright or side plates against which the wall panels of the blank may be folded. Two of these upright portions are visible at T3 and M, respectively. Against these portions the wall panels H and 2c of the blank are folded.

The die through which the plunger passes comprises, in essence, four die portions of which two are visible at 75 and 1b. The die portion i5 folds the wall panel H towards the plunger portion 73 and the die portion 56 folds the wall panel 2'4 towards the plunger portion M.

Four brackets may also be provided for supporting the flat blank above the die prior to the engagement of the blank by the plunger. These brackets may also assist in the folding operation. One of these brackets is shown at ll.

Turning now to the operation of the apparatus, the flat blank resting upon. the brackets ll is first engaged at the bottom panel !2 by the bottom surface of the plunger. The downward movement of the plunger causes the blank to fold first at the fold lines I5 due to the fact that the die portion I5 is somewhat taller than the die portion 16. The die portion 75 is recessed at 18 for length sufiicient to accommodate the width of the wall panel ll. As the blank moves downwardly towards the die aperture, the corner flap 35 is engaged by the side wall ls of the recess 18 and is folded towards the plunger, whereby an opening 80 is automatically formed, into which the lock tab 43 is subsequently inserted. Shortly after folding of the corner flap 35 the wall panel 24 of the blank is engaged by the lower die portion 6 and is folded towards the plunger Wall 14. Immediately prior to the folding of the Wall panel 24 about its fold line 25 the lock tab 43 becomes engaged by the die portion l5 initiating folding of the lock tab about its fold line 4'5.

As the folding of the wall panel 24 proceeds,

the lock tab 43 movestowardsxthe aperture 80.

6 On its path the lock tab is deflected by a pris matic portion 8i on'the die member 15 into the aperture 89 and past the internal tongue 65.

During the final stage of the assembly operation the wall panel 24 is swung into upright position with respect to the bottom panel [2 of the box. This causes the lock tab 43 to enter fully into the aperture 30 until its bordering locking edge 63 engages the corresponding locking edge 67 in the Wall panel ll.

It is quite apparent that insertion of the lock tab d3 into the aperture-requires a certain amount of force which must be exerted against the wall panel 24 by the die portion 16. Also the folding of the wall panel 2:4 at the fold line 26 requires a certain amount of force. As a result, the wall panel 24 has a tendency of curving slightly in the same sense as the top surface of the die por-' tion it is curved. This is somewhat undesirable since, if the curving i substantial, it is likely to result in an insertion of the lock tab 63 not quite far enough for the locking edge 63 to engage the locking edge 6"! in the panel II.

In order to overcome the tendency of curling of the panel 24, the side fold line ll, along which the lock tab is hinged to the wall panel 24, is made as long as possible, and preferably extends to the box corner proper, thatis to the point of intersection of the fold lines 15 and 26.

A similar stiffening effect is produced upon the wall I l by the corner flap 35. It is thus apparent that the 45 degree edge at the lock tab 43 and the corner flap provides advantages in the setting up of the blank into box form.

At the end of its stroke the plunger clears the lower edge of the die and the formed and locked box A is stripped off. The box is shown in perspective in Figure 2. It is ready for filling with merchandise, whereafter it may be closed. Clos ing of the box involves infolding of the front flap i8, folding of the cover side flaps 29 and 38, folding of the cover panel about its fold line H, and insertion of the flaps 29, 30, and 2! into the slots El, 28 and 23 respectively. These operations may be performed on automatic. box closing machinery which does not form a part of the present invention. Since the box folding and the locking operations occur simultaneously at all four box corners, the time for setting up the box and locking its corners is extremely short, and requires no more than a fraction of a second. The complete absence of the gluing operations eliminates the necessity of maintaining the box in the machine for a predetermined period of time. The box machine can for this reason be extremely small and can be operated at a rapid rate. The small size of the machine which only stands approximately sixty inches tall is an important factor since size of the machine enters the production cost of the boxes in two respects, firstly as required factory space, and secondl as machine cost since the cost of a machine is, to some extent, proportional to its size.

The: invention thus provides an extremely economical type of box. The box is attractive in appearance since its corner locks are practically concealed. In the specific form of box shown in Figure 2 only small portions of the lock tabs are visible. This is not objectionable in boxes of the illustrated type since such boxes are generally overwrapped after filling. Nevertheless. as will be shown further below, the form of, the internal cut at the corner may be modified in such a way as to conceal the lock tab in its entirety. Before turning to such modifications the formation of a lined box corner will be considered.

The corner construction of the box blank B shown in Figure 4 corresponds essentially to that of A shown in Figure l and the same reference numerals are used to identify corresponding portions. The box blank B is combined with a liner C which may be of any suitable lining material, for example, cellulose acetate or any other film commonly employed as box lining material. The liner C may be spot glued to the blank B, or it may be combined with it without an adhesive bond between the board and the liner. The edges of the liner may coincide with the edges of the blank or they may extend a short marginal distance d beyond the edge of the box blank. When the box corner is formed in the manner shown in Figure 3, the liner is automatically folded into a neat bellows fold or gusset 82 by reason of the edge H of the corner fiap acting as a guide or rule determining the creasing of the liner.

The internal cut which borders the internal tongue 55 comprises the locking portion 5'! which engages the locking edge 63 of the lock tab 43. The direction of the cut 61 is preferably of the order of 45 degrees with respect to the side fold line 39, but may be less. In order to facilitate entry of the lock tab into the internal cut, it is advantageous to provide an angular outline for the internal cut 5! such that a point id is formed within the body of the panel i i rather than. within its attached corner flap 35. This may be ac complished by a cut portion 83 which forms a sloping guiding edge on the flap 35. This sloping edge continues without change in direction past the fold line into the body of wall panel i i and guides the lock tab 43 into its proper position without danger of jamming or crowding of the board at the fold line 39. The guiding edge provided by the portion 83 may assume various other forms depending on the specific configuration of the internal out 5!, the basic principle being that two angularly disposed portions such as 5? and 33 are provided which form between them an angle or point 84 lying within the body of the panel i I rather than within the body of the flap 35. This particular structure facilitates insertion of the lock tab 33, it being manifestly optional what particular shape the internal cut 5! assumes below the portion 83, that is between the portion 83 and the fold lines 15, 41.

Figure 6 shows a modification of the corner construction shown in Figures 1 and 4.- which provides for the formation of a bellows fold by the board itself at the base of the corner. Identical reference characters identify identical parts and primed reference characters are applied to identify modified parts of the corner construction.

The corner fiap 35' is bordered by a sloping cut edge H extending at approximately 45 degrees from the end of the corner flap 35 to the lock tab 43'. The extension of the edge I! between the lock tab 43 and the corner proper is formed by a score 85 which may be a cut score to provide for easy folding. The cut edge bordering the lock tab 43' is extended at 86 to the fold line 47. The internal cut 5! may be of the same general configuration as shown in Figure 4. It is shown in Figure 6 with a slight modification of shap resulting in complete concealment of the lock tab 43' after formation of the corner. The internal cut 5| includes a locking portion 57, a guiding portion 83, and then continues substantially parallel to the fold line 39 at 81 extending back into the body of the side wall at 88. The corner is formed and locked in the same manner as previously described. Figures 7 and 8 illustrate the inside and the outside appearance, respectively, of the locked corner.

Figures 9 and 10 show a minor modification of the lock of Figures 6, '7 and 8. In the forms shown in Figures 9 and 10 the bellows iold at the base of the box corner is omitted, but the lock tab is concealed in its entirety.

In the blank shown in Figure 9 the internal cut 5|" extends closer to the base of the corner, the intersection of fold lines l5 and 26. The end of the cut 88 is spaced from the fold line 5 a distance sufiicient to provide a secure hinge portion for the corner fiap 35 at the base of the corner. It is advantageous in this connection to offset the fold line 39 with respect to the fold line 26. The offset is preferably greater at the base of the corner than it is at the top of the panel l I. The finished box corner is shown in Figure 10. Its resemblance to a glued box corner is striking, there being a complete absence of conspicuous lock flaps overlying the wall panels on the outside. This not only enhances the appearance of the box but also provides mechanical advantages because of the absence of protruding parts.

The internal cut whose locking portion ill in the previous figures were shown as being in substantial line-to-line coincidence with the locking edge 63 of the lock tab may be modified slightly by providing an angular end portion 89 shown in broken lines in Figure 9. The modification is illustrated in detail in Figures 11 and 12 showing the blank after setting up into corner shape. The angular portion 89 provides an edge beyond which the tip portion 90 of the lock tab projects after insertion of the lock tab 43 into the internal cut 5|. The tip portion may then be pulled to the inside of the box by movingthe lock tab 43 in the direction of the arrow 9!. This causes the tip portion to snap past the edge 89) thus pro viding a safety catch, so to speak, preventing accidental disengagement of the corner lock even under the most unfavorable conditions.

The invention thus provides an improved corher look for setting up folding boxes without the use of adhesive possessing numerou features and advantages which make the novel lock superior to glueless constructions heretofore proposed and more economical to produce than a glued box construction.

Obviously various modifications, additions, omissions, substitutions and other changes are possible within the scope of the invention without departure from its principles.

What is claimed is:

l. A glueless corner construction for folding boxes, comprising a base panel; a first wall panel hingedly extending from the base panel along a first base fold line; a second wall panel hingedly extending from the base panel along a second base fold line forming an angle with said first base fold line; a corner fiap hingedly extending from said first wall panel along a firsu side fold line, said first wall panel having an internal out of bent outline therein forming an internal tongue in said first wall panel, the tongue pointing towards, and extending substantially to, said first side fold line, whereby an aperture is automatically formed at the corner upon folding of said flap with respect to said first wall panel; and a lock tab hingedly extending from said second wall panel along a second side fold line which second side fold line lies in substantial coincidence with said first side fold line when said hingedly extending from the: base panel along;-

a first base fold'line; a second wall panel hingedly:

extending from the base panel along a second-1 base fold line forming an angle with saidi first"- base fold line; a-substantiall y triangular corner flap joined to said first wall panel along a first side fold line, said first wall panel having an internal out of bent outline therein forming: an:

internal tongue in said firstwallpaneli the pointing towards and extending with. its tip portion beyond; said side fold: line, whereby an aperture is automaticallyformed at the cor:- ner upon folding of said'fiap with respect to said first wall panel; and a lock tab hingedly extend.- i'ng from said second wall panel along a": second side fold line which second side fold line lies substantial coincidence with said first side fold line when said panels are in corner formingiposition, said lock tab being insertable through said? aperture and said out to underlie said first wall paneland said internal tongue and having a bordering locking edge extending fromsaid second sidefol'd line adapted to engage said internal cutin said first wall panel adjacent said first side fold line when said panels are in corner forming position.

3. A glueless corner construction for folding boxes, comprising a base panel; a first wall panel hingedly extending from the basepanel' along a first base fold line; a second wall" panel hingedly extending from the base panel along a-second base foldline forming an angle with said first base fold'line; a corner fiap hingedly extending from said first wall panel along a first side fold line,.

said first wall panel having an internal cut of' bent outline therein forming an internal tongue in said first wall panel, the tongue-pointing towards, and extending substantially to, said first side fold line, whereby an aperture is automatically formed at the corner upon folding 0t said fiap with respect to said first wall panel; and a lock tab hingedly extending from said second wall panel along a second side fold line which second side fold line lies in substantial coincidence with said. first: side. foldi line when said panels are in corner formingposition, saidlock tab extending to said secondbasev fold line at the point of. intersection of said secondl'side foldline with said second base fold line and-'beinginsertable through said aperture and' aid cut to-underlie said first wallpanel and said. internal tongue and having a bordering locking edge extending from said second side foldline adapted to engage said internal cut in said first wall panel adjacent said first side fold line when said panels. arein corner forming position, said lock tab by reason of it extending to said second base fold line also stiffening said second wall panel against curving during insertion of the tab into said aperture.

4. A glueless corner construction for folding boxes, comprising a base panel; a first wall panel hingedly extending from the base panel along a first base fold line; a second wall panel hingedly extending from the base panel along a second 10-. base foldline: forming: an angle with. said first? base. fold: line; a; substantially triangular: corner: fiapjoined to. said; first wall panel along alfirs't Sid@=fO1d, 1-iII,. the edge of the flap.- which extends.

from; thez intersection of? said: first side fold line-- with the first base fold: line forming. an. angle of substantially 4'52 degrees. with: said. first side fold line; said first wall panel having an internal cut of bent outline therein forming an internal tongue said. first: wall panel, the. tongue pointing;

towards, and; extending substantially to, said first sea iol'crl'inenwherenp an aperture is automaticailiy iionnediat the corner upon folding. of said flapwiths respect to said: first Wall panel; and a lock: hingedly; extending. from said second wall panel along a second side fold line which. second side fold line lies in substantial. coincideno'ea with. said first: side. foldt line when said panels are incorner. forming position, said lock t'aba being: inserta'blez through said aperture and;

saidl cut'toiunderlie saidifirst wall panel and said:

internal tongue: and: having a bordering: 10cking:

edge extending from: said. second side fold line adapted to engage said internal cut in said first wall: panel. adjacent-said. first side fold line when said panels-are in corner forming position.

52;, A". glu'elessa corner construction for folding: b'oxesgcomprising a base panel; a first wall. panel hingedlyr extending from. thev base panel along a firstbase fol'dsline; a second Wall panel hingedly extending: from the: base panel along a second base:- fold: line forming an: angle with said first base fO1d. 1llle;f a. substantially triangular corner flap joined to said first: Wall panel along a first side'foldlineth'e edge of the fiap'which extends from. the 'inte'rsection. of: said first side fold line with the'firstbase foldline forming an angle of substantially 45 degrees withsaid first side fold line,.said first wall panel having aninternal cut ofbe'nt outline therein'formingan internal tongue in said-t first; wall panel, the" tongue pointing. towards and-extending substantially to, said first side fold: line, whereby an aperture is automaticallyformed: at thercornerupon folding of said fiap with. respect. to said first Wall panel; and a lock=1tab hinge'dly exten'dingifroin said second wall panel-:- along; a. second-f sidetfold: line which second sidesi'o'ld line: lies: in substantial coincidence withsaidifirstfold-linez'when saidpanels are in corner forming position, saioi lo'cle tab having atipp'ort-i'oniout from the? stock of; said corner flap and extending; tlie flat blank; beyond said 45 degree edge, said l'ocktab beingihsertable, with its tip portion.lea-ding:,' into said aperture and said out to -underlie said first: wall panel and saidinternal tongue and having a bordering locking edge extending from said second side'fold lineadapted to engagesaid internal out in said first wall" panel adjacent said first sidefoldline-when said panels' are in cornenfornii-ng po'sitioni 6Z-A glueless' cornerconstruction for folding comprising a base'panel; a-first w'all'panel hingedly extendingfrom the base panel along a first base fold'linega second wall panel hingedly' extending-'troin'the base' panel alonga second tab hingedly extending from said second wall panel along a second side fold line which second side fold line lies in substantial coincidence with said first side fold line when said panels are in corner forming position, said lock tab being insertable through said aperture and said out to underlie said first wall panel and said internal tongue and having a bordering locking edge extending from said second side fold line adapted to engage said internal cut adjacent said first side fold line when said panels are in corner forming position; and a substantially triangular gusset panel adjacent the intersection of said first side fold line with said second side fold line, said gusset panel being hingedly connected to said second wall panel and to said corner fiap respectively.

7. A glueless corner construction for folding boxes, comprising a base panel; a first Wall panel hingedly extending from the base panel along a first base fold line; a second wall panel hingedly extending from the base panel along a second base fold line forming an angle with said first base fold line; a corner fiap hingedly extending from said first wall panel along a first side fold line, said first wail panel having an internal cut of bent outline therein forming an internal tongue in said first wall panel, the tongue pointing towards, and extending substantially to, said first side fold line, whereby an aperture is automatically formed at the corner upon folding of said fiap with respect to said first wall panel; and a lock tab hingedly extending from said second wall panel along a second side fold line which second side fold line lies in substantial coincidence with said first side fold line when said panels are in corner forming position, said lock tab being insertable through said aperture and said out to underlie said first Wall panel and said internal tongue and having a bordering locking edge extending from said second side fold line, said locking edge being in substantial edge-to-edge alignment with the portion of said internal out immediately adjacent said first side fold line when said panels are in corner forming position.

8. A glueless corner construction for folding boxes, comprising a base panel; a first wall panel hingedly extending from the base panel along a first base fold line; a second wall panel hingedly extending from the base panel along a second base fold line forming an angle with said first base fold line; a corner flap hingedly extending from said first wall panel along a first side fold line, said first wall panel having an internal cut of bent outline therein, said out extending beyond said first side fold line and forming an internal tongue in said first wall panel, the tongue pointing towards, and extending beyond, said first side fold line whereby an aperture is automatically formed at the corner upon folding of said fiap with respect to said first wall panel, said internal out including a substantially straight engagement portion remote with respect to said first base fold line and a second portion closer to said first base fold line, said second portion extending at an angle with respect to said engage ment portion, the said two portions defining a tip on said tongue, said tip lying within said first wall panel; and a lock tab hingedly extending from said second wall panel along a second side fold line which second side fold line lies in sub stantial coincidence with said first side fold line when said panels are in corner forming position, said lock tab being insertable through said aperture and said out to underlie said first wall panel and said internal tongue and having a bordering locking edge extending from said second side fold line adapted to engage the engagement portion of said internal cut adjacent said first side fold line when said panels are in corner forming position.

9. A glueless corner construction for folding boxes, comprising a base panel; a first wall panel hingedly extending from the base panel along a first base fold line; a second wall panel hingedly extending from the base panel along a second base fold line forming an angle with said first base fold line; a corner flap hingedly extending from said first wall panel along a first side fold line, said first wall panel having an internal cut of bent outline therein, said out comprising two distinct portions, a first portion extending substantially parallel to said first side fold line, and a second portion extending at an angle with respect to the first portion into the body of the said first wall panel, said second portion being farther remote from the intersection of the first base fold line with the second base fold line than the first portion of the cut, the cut forming an internal tongue in said first wall panel, the tongue pointing towards, and extending substantially to, said first side fold line, whereby an aperture is automatically formed at the corner upon folding of said flap with respect to said first wall panel; and a lock tab hingedly extending from said second wall panel along a second side fold line which second side fold line lies in substantial coincidence with said first side fold line when said panels are in corner forming position, said lock tab being insertable through said aperture and said out to underlie said first wall panel and said internal tongue and having a bordering locking edge extending from said second side fold line adapted to engage the second portion of said internal cut when said panels are in corner forming position.

- REGINALD B. MELLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 648,385 Burns May 1, 1900 691,458 Ferres Jan. 21, 1902 762,724: Kane June 14, 1904 1,081,981 Palmer Dec. 23, 1913 1,129,909 Simoneaux Mar. 2, 1915 2,445,036 Moore July 13, 1948 2,476,253 Van Rosen July 12, 1949 2,488,703 Buttery Nov. 22, 1949 2,573,379 Acker Oct. 30, 1951 

